Editing armature in edit mode mess up pose mode
You should not edit the bones in edit mode after animating them, do that only if you want to modify the rest pose.
If you want to pose the bones than use Pose mode. Editing bones after posing will break the pose because you have modified the original rest pose and the transformation matrices of all the bones would evaluate a wrong pose. because poses are relative to the Rest_Pose.

you need to setup your rest pose while in edit mode (or in pose mode and use  Apply Pose as Restpose) and then proceed to posing the character, without modifying the rest pose.